In order to apply a photosensitive emulsion onto a printing screen, an emulsion bucket is slidably contacted with a surface of the screen which is vertically set, thereby applying the emulsion thereon.
An automatic emulsion-applying means of such type is described in Japanese Patent Publication 58-53332 and its improvement is disclosed in Japanese Laid-open Application 59-171958 belonging to the present applicant. Since a viscous emulsion is applied onto a mesh screen of a printing-plate in either one of these systems, the applying procedure must be repeated in several times for providing a suitable thickness of an emulsion film. Further, a viscosity and amount of the emulsion as well as an applying pressure of the emulsion bucket to the screen must be adjusted to achieve the correct thickness of the emulsion film, resulting in a troublesome operation.
For the improvement, the applicant has proposed apparatus in, for example, Japanese Laid-open Application 60-188949 and Japanese Laid-open Application 61-113063 for applying the emulsion of a pedetermined thickness onto the screen by use of an emulsion screen film which has previously formed as an emulsion film of the same thickness.
One of such proposed systems is shown in FIG. 8 wherein a vertically supported printing-screen S is provided securely with an emulsion screen film F of a predetermined size by means of an adhesive tape and wherein the printing-screen is pressed by an emulsion bucket B on the side of the emulsion screen film F while the opposite side is supplied with an emulsion D. Another proposed system is shown in FIGS. 9 and 10 wherein a back board R with a rubber or flexible foamed resin is arranged behind the printing-screen S and wherein the opposite side is supplied with the emulsion D by the emulsion bucket B. In this manner, the emulsion bucket B containing the emulsion D is slidingly contacted to the opposite side of the printing-screen S provided with the emulsion screen film F for wetting the emulsion layer of the screen film F, thereby securely applying the emulsion film onto the screen. These methods utilize the emulsion screen film F, which has previously been formed into the membrane of the predetermined thickness, so that the printing-screen S having the emulsion film of an accurate thickness may be prepared.
As described hereinabove, the use of such emulsion screen film F is very effective but requires additional steps of positioning the emulsion film accurately on the screen surface, securely applying the film thereto, cutting the film in a required length and others.
In order to support the emulsion screen film F of the required size on the screen surface, for example, an operator must support the film manually or the back board R must be provided behind the emulsion screen film F. These procedures are essentially manual and thus very troublesome. Further, incorrect support of the film cannot provide the advantage of utilizing the emulsion screen film F, such as the accurate thickness of the film.
According to the system of FIG. 8 in particular, even the pressure of the emulsion bucket on the emulsion screen film F against the printing-screen cannot readily be adjusted uniformly. According to the system as shown in FIGS. 9 and 10, on the other hand, a larger size of the emulsion bucket B than a size of the emulsion screen film F may pass the emulsion D through the screen on the either side of the emulsion screen film F, thereby contaminating the back board R with the emulsion. Thus, after the application the emulsion D must be removed from the back board R, resulting in a troublesome procedure.
Accordingly an object of the invention is to provide an automatic appartus for applying an emulsion screen film of screen-printing which enables the convenient and rapid operation of positioning the emulsion film accurately on the screen surface, securely applying the film thereto, cutting the film in a required length and others.